A wide variety of portable electrical devices are available today including, but not limited to, laptop computers, personal digital assistants, mobile phones, and cordless power tools. Such portable electrical devices may utilize a rechargeable battery for providing power to operate the device in a battery supply mode. An adapter such as an ACDC or DCDC adapter may also be available to supply power to the portable electrical device in an adapter supply mode. The rechargeable battery may or may not be charged in the adapter supply mode depending on the presence and condition of the rechargeable battery. In some instances, it is advantageous to supply a system load of the portable electrical device with power from both the adapter and the rechargeable battery. To do so, some conventional embodiments have controlled the output voltage of the adapter but have not adjusted the output voltage of the rechargeable battery.
Accordingly, there is a need for adjusting the output voltage of a rechargeable battery to enable the rechargeable battery and adapter to simultaneously provided power to a load of the portable electrical device.